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United States Patent |
5,522,689
|
Cucchi
|
June 4, 1996
|
Device with improved bar guide for loading bars in automatic lathes
Abstract
A device (10,110) for loading bars in an automatic lathe comprises guide
means (19,119,119') along which is supported and made to run a bar
(12,112) with leading end projecting from said guide means to be inserted
in a lathe chuck (11,111) to be grasped by handling means (21,121) of the
lathe moving parallel to the bar axis to feed the bar under machining
tools (31,131). At least a first part of the guide means (19,119,119')
nearest the chuck has kinematic connection with the handling means
(21,121) for moving axially and substantially synchronously therewith.
Inventors:
|
Cucchi; Pietro (Bussero, IT)
|
Assignee:
|
Pietro Cucchi S.p.A. (IT)
|
Appl. No.:
|
194685 |
Filed:
|
February 10, 1994 |
Foreign Application Priority Data
| Feb 19, 1993[IT] | MI93A0318 |
| Jun 11, 1993[IT] | MI93A1245 |
Current U.S. Class: |
414/14; 82/127; 226/165 |
Intern'l Class: |
B23Q 005/22 |
Field of Search: |
414/18,14,17,751
82/124,126,127
198/748,586
226/102,128,129,165
|
References Cited
U.S. Patent Documents
4068546 | Jan., 1978 | Werkmeister | 82/127.
|
5170685 | Dec., 1992 | Cucchi | 414/14.
|
Primary Examiner: Underwood; Donald W.
Attorney, Agent or Firm: Shlesinger, Fitzsimmons & Shlesinger
Claims
What is claimed is:
1. In an automatic lathe having thereon movable bar feed means, a device
for loading bars into the lathe comprising a frame, guide means on said
frame along which is supported and made to run a bar having a leading end
thereof projecting from said guide means to be inserted into said lathe to
be grasped by said bar feed means for movement thereby parallel to the
axis of said bar to effect the feeding of the bar into registry with the
machining tools of the lathe, and characterized in that at least a first
part of the guide means nearest the lathe is movable and is connected by a
tierod to said bar feed means for movement thereby axially with said bar
and substantially synchronously therewith at least a second part of the
guide means following the first part thereof comprising a series of
aligned guide sections supported on said frame for movement in the
direction or the bar feed, and interconnected to each other by elastic
connections, and the first section of the series thereof being connected
to said first part and the last section of the series being connected to a
fixed point on said frame by further elastic connections in such a manner
that the movement of the first part causes said sections to draw apart and
together substantially synchronously with said movement of said first
part.
2. The invention in accordance with claim 1 characterized in that each
elastic connection comprises stop means operative to prevent the
withdrawing of the sections apart from each other beyond a pre-set amount.
3. The invention in accordance with claim 1 characterized in that said at
least first part of the guide means is supported on said frame by a truck
movable in the bar feed direction.
4. The invention in accordance with claim 1 characterised in that each of
the guide sections is supported by a carriage running on a guide extending
in the bar feed direction.
5. The invention in accordance with claim 1 characterised in that the guide
means comprises a plurality of generally annular elements mutually
coaxially aligned to be traversed axially by the bar.
6. The invention in accordance with claim 1 further including a pusher
having a forward end engagable with a tail end of said bar and operable to
push said bar axially along the guide means to insert the leading end of
the bar into the lathe.
7. The invention in accordance with claim 6 including means for operating
the pusher, and wherein said operating means comprises a powered chain to
which is constrained a rear end of the pusher.
8. The invention in accordance with claim 6 characterised in that the
pusher has its forward end bearing a clamp for grasping the tail end of
the bar.
9. The invention in accordance with claim 7 characterised in that the
operating means for the pusher further comprises a hydraulic motor.
10. In an automatic lathe having thereon reciprocable bar feed means, a
device for loading bars into the lathe comprising a frame, movable guide
means on said frame defining an elongate passage for supporting therein a
bar that is to be inserted into said lathe, a pusher movable on said frame
independently of said guide means and extending into one end of said
passage, said bar having a trailing end thereof engagable by said pusher
to be pushed thereby relative to said guide means toward said lathe, and
having a leading end thereof projecting from the opposite end of said
passage to be grasped by said bar feed means for movement thereby parallel
to the axis of said bar to effect the feeding of the bar into registry
with the machining tools of the lathe, and means securing at least a first
part of said movable guide means nearest the lathe to said bar feed means
for reciprocation substantially synchronously therewith.
11. The invention in accordance with claim 10, characterized in that at
least a second part of said guide means following said first part thereof
is made up of a series of aligned guide sections supported on said frame
for movement in the direction of the bar feed, and interconnected to each
other by elastic connections, and the first section of the series thereof
being connected to said first part and the last section of the series
being connected to a fixed point on said frame by further elastic
connections in such a manner that the movement of the first part causes
said sections to draw apart and together substantially synchronously with
said movement of said first part.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a device for sequentially loading bars in
an automatic lathe. Specifically it relates to a bar loader having an
improved bar guide system.
In the known art there are automatic lathes which receive sequentially by
means of special loaders bars from which to make parts or machined
sections. The loader inserts axially the end of a bar at the rear of the
lathe chuck. The chuck comprises a clamp or headstock which grasps the bar
and moves it axially beneath the machining tools for a length
predetermined to be the actual length of the work to be machined. After
completion of machining of the work it is cut off and the clamp withdraws
by running along the bar to return to the starting position, grasp the bar
again and again advance to feed beneath the tools the section to be
machined. The sequence of operations is repeated until the bar is
exhausted. At this point the loader withdraws the remaining bar stub,
discards it and inserts a new bar in the lathe so that the machining cycle
can resume automatically.
There being inserted in the lathe only a short section of bar head, for the
entire machining cycle the bar is supported at the rear by guide means
integral with the loader structure. In known loaders, between the feed
clamp and bar guide means there is however inevitably created
progressively an ever greater space as the clamp moves to push the bar
into the lathe. This allows bending and vibration of the bar which disturb
machining performed by the lathe. In addition, the resonance vibrations
produced in particular at the higher rotation speeds of the bar are
difficult to damp by conventional methods of elastic suspension, the
resonance frequency continuing to change depending on the breadth of the
free space between the clamp and the guides.
SUMMARY OF THE INVENTION
The purpose of the present invention is to overcome the above shortcomings
by supplying a device for loading bars into automatic lathes which would
minimise the free spaces between the lathe and the guide means for the bar
in the loader and make as uniform as possible the guidance of a bar fed to
the lathe chuck.
In view of said purpose it is sought in accordance with the present
invention to provide a device for loading bars into an automatic lathe
comprising guide means along which is supported and made to run a bar with
leading end projecting from said guide means to be inserted in a lathe
chuck to be grasped by lathe handling means moving parallel to the bar
axis to feed the bar under machining tools. At least a first part of the
guide means nearest the chuck has kinematic connection with the handling
means for moving axially and substantially synchronously therewith.
BRIEF DESCRIPTION OF THE DRAWINGS
To clarify the explanation of the innovative principles of the present
invention and its advantages compared with the known art there is
described below with the aid of the annexed drawings a possible embodiment
thereof by way of nonlimiting example applying said principles. In the
drawings:
FIG. 1 shows a partial schematic cross section of a first embodiment of a
bar loader in accordance with the present invention, and
FIG. 2 shows a partial schematic cross section of a second embodiment of a
bar loader in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
With reference to the figures FIG. 1 shows a machining unit or station made
up of a loader 10 and a lathe. Of the lathe there is shown schematically
only the chuck assembly 11 the rest being easily imagined by those skilled
in the art and not affecting the present invention.
The loader supplies sequentially a bar 12 by inserting it axially into the
lathe chuck assembly. For this purpose the loader comprises a pusher 13
aligned with the loading opening of the chuck 11 and bearing at its head a
clamp 14 for grasping the tail of the bar to be fed. The pusher 13 is
constrained at the rear to a cursor 32 displaced parallel to the extension
of the bar pusher 13, e.g. by means of a transmission chain 15 wrapped
around a pulley 16, 17. The chain is driven by a motor 18 (advantageously
of the hydraulic type) to cause the bar pusher to complete the bar loading
movements and withdraw the stub to be scrapped. Along the path of the bar
and the pusher are provided guide means 19, e.g. made up of a plurality of
annular elements aligned to form a guide and supported elastically for
damping of the vibrations produced by high bar speed rotation as is well
known in the field.
In FIG. 1 the bar is shown toward the end of its machining, i.e. when the
pusher has travelled almost the entire extension of the guide 19.
Naturally, the length of the guide and hence the extension of the pusher
and its travel will be proportionate to the length of the bar to be fed.
The loader can comprise also automatic sequential insertion means for the
bars in the clamp 14, taking the bar from a bar store, and automatic
unloading means from the clamp 14 of the residual stub. For the sake of
simplicity said automatic means are not shown. They are however commonly
used and therefore easily imagined by those skilled in the art. For
example, suitable means are shown in Italian patent application
MI92A000978 and patent IT 216 871. As shown in the above patent rights,
the guide 19 can open longitudinally to allow lateral insertion of the bar
taken from the store.
The lathe chuck comprises bar feed means made up of a clamp 20 for grasping
the bar and a bush 21 for reciprocating axial movement of the bar during
machining. For its movement, the bush 21 runs by means of a known drive 23
along a guide 22 parallel to the bar feed direction. The clamp 20 and bush
21 provide the above described feed movement `by sections`. Specifically,
after the bar has been inserted in the chuck by the loader, the bush 21
begins to feed the bar under the lathe tools shown schematically at 31.
After completion of the machining of a section, the bush withdraws by
running along the bar to return to the starting position shown in solid
lines in the figure and again grasps the bar to push it forward for
machining of the following section.
The above description applies to a basically known technology readily
imagined by those skilled in the art. For this reason, for example, there
are not shown and described in detail the elements which provide the
movements, openings and closings of the various chuck parts designed to
provide feed by sections. In accordance with the innovative principles of
the present invention the guide means extend to the proximity of the
moving bush of the lathe and at least their terminal part is kinetically
connected to the handling bush 21 of the lathe so as to follow its
movements while holding substantially unchanged the spacing between the
end of the guide means and the moving bush.
In the embodiment of FIG. 1 the guide means are supported by a truck 24
running in the bar feed direction. For example, the truck comprises a pair
of carriages 25, 26 running along a guide 27 supported on the loader
frame. The truck 24 is connected to the handling bush 21 of the lathe by
means of a tierod 30 so as to follow integrally its movements.
Advantageously the truck 24 can support the entire bar guide 19. The bar
will thus be supported uniformly along its entire length whatever the
position of the moving lathe bush. It is clear that the spacing between
the headstock and the guide means can be the least possible.
In use, initially the pusher is completely retracted and a bar is
positioned in the guide or in its initial part if the length of the guide
is greater than that of the bar, e.g. by known withdrawal means of the bar
from the store, as mentioned above. Upon operation of the motor 18 the
clamp 14 optionally aided by known bar locking means engages the bar at
the rear and begins pushing and insertion thereof into the lathe chuck.
When the bar has advanced into the chuck a pre-set amount the bush 21 is
operated to grasp the bar and then advance to feed the bar beneath the
lathe tools. Upon termination of its forward travel the bush returns to
the starting position to again grasp the bar and again begin forward
travel.
The bush movement is transmitted to the truck 24 through the bar 30 so that
there is not formed any variable space of the bar not supported between
the loader and the lathe. The bush can also move forward and backward
holding the bar to advance it beneath the tools.
During forward travel of the bush the motor 18 has its feed circuit
connected in discharge or under a slight pressure so that the pusher
follows the movement given to the bar by the bush without losing its grip
on the bar tail.
After termination of machining of the entire bar the motor 18 is reversed
so that the scrap bar stub is withdrawn from the lathe. Known unloading
means extract the bar stub from the clamp 14 and replace it with a new bar
to be machined.
Naturally the above description of an embodiment applying the innovative
principles of the present invention is given merely by way of example and
therefore is not to be taken as a limitation of the patent right claimed
here. For example, FIG. 2 shows a possible variation of the guide with
movement following the headstock to keep bar support substantially
uniform. To simplify the explanation, in FIG. 2 parts similar to those of
FIG. 1 are designated by the same reference number increased by 100. There
is thus a loader 110 feeding a lathe 111 a bar 112 by means of a pusher
113 bearing at its head a clamp 114 for grasping the tail of the bar to be
fed for sliding it along guide means 119,119' aligned with the chuck. The
chuck comprises a clamp or headstock 120 for grasping the bar and a bush
121 commanded to run along a guide 122 by means of a known drive 123 so as
to move the bar beneath the tools 131. In FIG. 2 the bush is shown in
solid lines and shaded in an intermediate position of its travel whose end
positions are shown schematically in broken lines. The pusher moving means
are not shown for the sake of simplicity. Said means can however be of any
known type. For example, they can be similar to those shown schematically
in FIG. 1.
The means of guiding the bar in the loader comprise a first part 119
supported by a first truck 125 connected to the headstock through a tierod
130 as for the embodiment of FIG. 1. After the first part 119 there
follows a plurality of guide sections or segments 119 arranged in series.
Each section 119 is supported by a base 124 having a truck 125 running
along a guide 127 parallel to the bar feed direction. The trucks are
interconnected in sequence through elastic connection means, e.g. provided
by traction springs 133 each arranged between adjacent trucks. The first
truck nearest the lathe is connected to the moving bush 121 by means of
the tierod 130 while the last truck in the series is connected to the
loader frame through a traction spring 134. Between adjacent trucks there
can also be advantageously placed connection elements 135 bearing the ends
of pins 136 running in grooves 137 placed on the bases of the trucks and
lengthened in the truck movement direction. The running grooves of the
pins have sufficient extension to permit against the action of the springs
reciprocal withdrawal of the various sections 119 when the moving bush 121
passes from its starting position to the final position.
Optionally there can be provided an initial fixed guide part 119'. Both the
first part 119' and the sections 119 can be made up of aligned annular
elements as described above for the guide 19.
In use, when the bush 121 pushes the bar into the lathe the sections 119
draw apart entrained by the tierod 130 against the action of the
interconnecting springs. When the bush completes the return movement, the
springs recall the sections, which draw together again. It is clear that
the distribution of the sections remains substantially uniform in every
position of the bush 121.
Although for drawing clarity the guide elements 119 are shown widely spaced
it is clear to those skilled in the art that the distance between said
elements can be very small, the relative travel between adjacent trucks
being a fraction of the bush travel and said fraction being given by the
total number of trucks. The maximum space formed between the guide
sections during movement of the bush can thus be reduced to a negligible
amount for bar support with minimum vibrations. For example, with a
relatively high number of carriages segments can pass from null spacing or
almost to a spacing not greater than that of two guide elements on the
same carriage.
At this point it is clear that the purposes have been met by supplying
loading devices which provide optimal support of the bar along its entire
extension and in particular in the critical zone between the lathe and the
loader. It has been found that with devices applying the principles
claimed here the vibrations are surprisingly reduced, allowing the lathe
machining with high precision.
The embodiments shown are naturally given by way of example and
modifications thereto can be readily imagined without thereby going beyond
the scope of the patent right claimed here. For example, the structure of
the loader and lathe can vary from those shown diagramatically depending
on the practical requirements and actual dimensions of the bars machined.
In addition, aligned with the moving guides on the loader side opposite
the lathe there can be or not be arranged fixed guides for initial support
of the bar or pusher. Finally, in addition to the guides other parts of
the loader can be supported by the truck connected to the headstock. The
loader can also be a multichuck loader.
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